A steel sheet for hot press comprises: a predetermined chemical composition; and a steel microstructure that includes ferrite and cementite and in which Mn/Mn is 1.4 or more, where Mn is a Mn concentration of the ferrite and Mn is a Mn concentration of the cementite.

A steel sheet for cans has a chemical composition containing, by mass %, C: 0.015% or more and 0.150% or less, Si: 0.04% or less, Mn: 1.0% or more and 2.0% or less, P: 0.025% or less, S: 0.015% or less, Al: 0.01% or more and 0.10% or less, N: 0.0005% or more and less than 0.0050%, Ti: 0.003% or more and 0.015% or less, B: 0.0010% or more and 0.0040% or less, and the balance being Fe and inevitable impurities. The steel sheet has a microstructure including a ferrite phase as a main phase and at least one of a martensite phase and a retained austenite phase as a second phase, the total area fraction of the second phase being 1.0% or more, and the sheet has a tensile strength of 480 MPa or more, a total elongation of 12% or more, and a yield elongation of 2.0% or less.

Provided are a high-strength steel sheet having a yield strength of 550 MPa or more and excellent fatigue-strength of a weld and a method for manufacturing the steel sheet.

A high-strength steel sheet has a specified chemical composition, a steel microstructure observed in a cross section in a thickness direction parallel to a rolling direction including 40% to 75% of a martensite phase in terms of volume fraction, in which a total volume fraction of martensite grains whose average grain diameter ratios with respect to adjacent ferrite grains are or more and 1 or less is 60% or more with respect to an entire martensite phase, and a yield strength (YP) of 550 MPa or more.

The present invention relates generally to steel compositions, methods of manufacturing the compositions and using the compositions to produce rimfire ammunition cartridges. The steel compositions for use in the rimfire cartridges are processed through cold-rolling and annealing steps to create suitable physical properties.

A steel sheet for hot press comprises: a predetermined chemical composition; and a steel microstructure that includes ferrite and cementite and in which Mn/Mn is 1.4 or more, where Mn is a Mn concentration of the ferrite and Mn is a Mn concentration of the cementite.

Disclosed is a steel whose composition includes specified wt % of: Ni, Mo, Co, Mo+Co+Si+Mn+Cu+W+V+Nb+Zr+Y+Ta+Cr+C+Al+B+Ti+N, Ni+Co+Mo, Al, Ti, N, Si, Mn, C, S, P, B, H, O, Cr, Cu, W, Zr, Ca, Mg, Nb, V, Ta, Y, the remainder being iron and impurities resulting from production. The inclusion population, observed by image analysis on a polished surface of 650 mm.sup.2 if the steel is in the form of a hot-formed part or a hot-rolled sheet and 800 mm.sup.2 if the steel is in the form of a cold-rolled sheet, does not include non-metal inclusions of an equivalent diameter greater than 10 m. Also disclosed are a product created from the steel, and a manufacturing method.

A steel sheet has a composition containing, in mass %, from 0.60 to 1.25% of C, 0.50% or less of Si, from 0.30 to 1.20% of Mn, 0.030% or less of P, 0.030% or less of S, from 0.30 to 1.50% of Cr, from 0.10 to 0.50% of Nb, from 0 to 0.50% of Ti, from 0 to 0.50% of Mo, from 0 to 0.50% of V, from 0 to 2.00% of Ni, the balance being Fe with unavoidable impurities. A ferrite phase as a metal matrix has dispersed therein cementite particles and NiTi based carbide particles. A number density (cross section parallel to rolling and thickness directions) of the carbide particles having a circle equivalent diameter of 0.5 m or more is from 3,000 to 9,000 per mm.sup.2 and a number density of voids having a circle equivalent diameter of 1.0 m or more is 1,250 per mm.sup.2 or less.

A steel sheet for crown cap having excellent formability from which a crown cap having an excellent pressure resistance can be produced without an expensive soft liner even if the steel sheet is subjected to sheet metal thinning, the steel sheet having: a chemical composition containing, in mass %, C: more than 0.006% and 0.012% or less, Si: 0.02% or less, Mn: 0.10% or more and 0.60% or less, P: 0.020% or less, S: 0.020% or less, Al: 0.01% or more and 0.07% or less, and N: 0.0080% or more and 0.0200% or less, with the balance being Fe and inevitable impurities; and a percentage of a region of more than 0% and less than 20% at a position of of a sheet thickness, the region having a dislocation density of 110.sup.14 m.sup.2 or less.

A steel sheet for crown cap having: a chemical composition containing, C, Si, Mn, P, S, Al, N, with the balance being Fe and inevitable impurities; a ferrite phase in a region from a depth of of a sheet thickness to a mid-thickness part, the ferrite phase having a standard deviation of ferrite grain size of 7.0 m or less; a yield strength of 560 MPa or more and 700 MPa or less in a rolling direction; and a difference of 25 MPa or more between a yield strength in a 2% strain tensile test and a yield strength in a tensile test after heat treatment at 170 C. for 20 minutes, in the rolling direction.

The present invention relates generally to steel compositions, methods of manufacturing the compositions and using the compositions to produce rimfire ammunition cartridges. The steel compositions for use in the rimfire cartridges are processed through cold-rolling and annealing steps to create suitable physical properties.